SelvedgeDefine the hexagon before counting
Enter the finished side S of a regular flat-top hexagon. Width = 2S; height = √3 × S. Side length is not overall diameter and excludes the seam or basting allowance.
A five-column, four-row example
Five columns of four 1-inch-side hexagons contain 20 pieces. Columns are 1.5S apart and alternate by half a hexagon’s height.
Width = S × (1.5 × columns + 0.5). With multiple columns, height = √3 × S × (rows + 0.5). The example spans 8 × 7.794 inches. One column omits the extra half.
Why an area estimate is not a cutting plan
The bounding box includes gaps at jagged edges; it is not a fully covered rectangle. No partial pieces, rosettes or edge trimming are calculated. Large diagrams show a labeled sample; numeric results retain the full count.
Keep fabric cutting separate from finished geometry
With perpendicular allowance A, cut side = S + 2A ÷ √3. A 1-inch side with ¼-inch allowance becomes about 1.289 inches.
This is geometry, not yardage. Nesting and motifs affect yield. Use separate square, block and batting calculations.